comparison: src/ring.h
src/ring.h
- changeset 19
- ed9685f44ab3
- child 24
- 1a0faaaceb84
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| 18:918b6c0f8b5b | 19:ed9685f44ab3 |
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| 1 /* | |
| 2 * LDForge: LDraw parts authoring CAD | |
| 3 * Copyright (C) 2013 - 2018 Teemu Piippo | |
| 4 * | |
| 5 * This program is free software: you can redistribute it and/or modify | |
| 6 * it under the terms of the GNU General Public License as published by | |
| 7 * the Free Software Foundation, either version 3 of the License, or | |
| 8 * (at your option) any later version. | |
| 9 * | |
| 10 * This program is distributed in the hope that it will be useful, | |
| 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 13 * GNU General Public License for more details. | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License | |
| 16 * along with this program. If not, see <http://www.gnu.org/licenses/>. | |
| 17 */ | |
| 18 | |
| 19 #pragma once | |
| 20 | |
| 21 namespace iter | |
| 22 { | |
| 23 namespace _imp | |
| 24 { | |
| 25 template<typename T> | |
| 26 class RingAdapter; | |
| 27 } | |
| 28 | |
| 29 template<typename T> | |
| 30 _imp::RingAdapter<T> ring(T& collection); | |
| 31 | |
| 32 template<typename T> | |
| 33 _imp::RingAdapter<T> ring(T& collection, int count); | |
| 34 } | |
| 35 | |
| 36 /* | |
| 37 * Implements a ring adapter over T. This class corrects indices given to the element-operator so that they're within bounds. | |
| 38 * The maximum amount can be specified manually. | |
| 39 * | |
| 40 * Example: | |
| 41 * | |
| 42 * int A[] = {10,20,30,40}; | |
| 43 * ring(A)[0] == A[0 % 4] == A[0] | |
| 44 * ring(A)[5] == A[5 % 4] == A[1] | |
| 45 * ring(A)[-1] == ring(A)[-1 + 4] == A[3] | |
| 46 */ | |
| 47 template<typename T> | |
| 48 class iter::_imp::RingAdapter | |
| 49 { | |
| 50 private: | |
| 51 // The private section must come first because _collection is used in decltype() below. | |
| 52 T& collection; | |
| 53 const int count; | |
| 54 | |
| 55 public: | |
| 56 RingAdapter(T& collection, int count) : | |
| 57 collection {collection}, | |
| 58 count {count} {} | |
| 59 | |
| 60 template<typename IndexType> | |
| 61 decltype(collection[IndexType()]) operator[](IndexType index) | |
| 62 { | |
| 63 if (count == 0) | |
| 64 { | |
| 65 // Argh! ...let the collection deal with this case. | |
| 66 return this->collection[index]; | |
| 67 } | |
| 68 else | |
| 69 { | |
| 70 index %= this->count; | |
| 71 | |
| 72 // Fix negative modulus... | |
| 73 if (index < 0) | |
| 74 index += this->count; | |
| 75 | |
| 76 return this->collection[index]; | |
| 77 } | |
| 78 } | |
| 79 | |
| 80 int size() const | |
| 81 { | |
| 82 return this->count; | |
| 83 } | |
| 84 }; | |
| 85 | |
| 86 /* | |
| 87 * Convenience function for RingAdapter so that the template parameter does not have to be provided. The ring amount is assumed | |
| 88 * to be the amount of elements in the collection. | |
| 89 */ | |
| 90 template<typename T> | |
| 91 iter::_imp::RingAdapter<T> iter::ring(T& collection) | |
| 92 { | |
| 93 return {collection, countof(collection)}; | |
| 94 } | |
| 95 | |
| 96 /* | |
| 97 * Version of ring() that allows manual specification of the count. | |
| 98 */ | |
| 99 template<typename T> | |
| 100 iter::_imp::RingAdapter<T> iter::ring(T& collection, int count) | |
| 101 { | |
| 102 return {collection, count}; | |
| 103 } | |
| 104 | |
| 105 template<typename T> | |
| 106 int countof(const iter::_imp::RingAdapter<T>& ring) | |
| 107 { | |
| 108 return ring.size(); | |
| 109 } |
